Php – “It is not safe to rely on the system’s timezone settings”

I have a script that I completed a week ago, without any problem or bug. Today, I tested it again and I received these messages:

Strict Standards: date() [function.date]: It is not safe to rely on
the system's timezone settings. Please use the date.timezone setting,
the TZ environment variable or the date_default_timezone_set()
function. In case you used any of those methods and you are still
getting this warning, you most likely misspelled the timezone
identifier. We selected 'Europe/London' for '1.0/DST' instead in
C:\Users\xx\VertrigoServ\www\login\PHPMailer\class.phpmailer.php on
line 1925

Strict Standards: date() [function.date]: It is not safe to rely on
the system's timezone settings. Please use the date.timezone setting,
the TZ environment variable or the date_default_timezone_set()
function. In case you used any of those methods and you are still
getting this warning, you most likely misspelled the timezone
identifier. We selected 'Europe/London' for '1.0/DST' instead in
C:\Users\xx\VertrigoServ\www\login\PHPMailer\class.phpmailer.php on
line 1929

I already set in the php.ini ;date.timezone = "Europe/Lisbon" and the same occurs. I've already restart the server

Any ideas?